1. Field of the Invention
This invention relates to a tensioner for an endless power transmission belt or the like as well as to a method of making such a tensioner.
2. Prior Art Statement
It is known in the art to provide a tensioner for a power transmission belt that is adapted to be operated in an endless path, the tensioner comprising a support means for being fixed relative to the belt, a belt engaging means carried by the support means and being movable relative thereto, and mechanical spring means operatively associated with the support means and the belt engaging means for urging the belt engaging means relative to the support means and against the belt with a force to tension the belt.
Examples of tensioners of the above mentioned type are provided in the following five United States patents:
(1) U.S. Pat. No. 3,413,866--Ford PA1 (2) U.S. Pat. No. 4,108,013--Sragal PA1 (3) U.S. Pat. No. 4,145,934--Sragal PA1 (4) U.S. Pat. No. 4,151,756--Binder et al PA1 (5) U.S. Pat. No. 4,249,425--Watson PA1 (8) U.S. Pat. No. 3,602,054--Jackson et al. PA1 (9) U.S. Pat. No. 3,802,286--Winklhofer et al.
It appears from item (1) above that a tension spring urges an idler pulley in tensioning engagement against a belt.
It appears from item (2) above that a compression spring urges an idler pulley in tensioning engagement against a belt.
It appears from item (3) above that a leaf spring urges an idler pulley in tensioning engagement against a belt.
It appears from item (4) above that a plurality of bi-metal dish-shaped springs disposed in various stacked relations thereof urge an idler pulley in tensioning engagement against a belt.
It appears from item (5) above that pneumatic means is adapted to threadedly adjust an idler pulley rod of a belt tension wherein a pair of dish-shaped springs urge the idler pulley in tensioning engagement against a belt.
It is also known in the art to provide a piston and cylinder arrangement for hydraulically urging an idler pulley in tensioning engagement against a belt.
For example, see the following two United States patents:
(6) U.S. Pat. No. 3,142,193--Polko
(7) U.S. Pat. No. 4,276,038--Kraft
It is also known to provide a belt tensioner where friction surface dampening means of the solid type are utilized to tend to dampen vibrations and the like that are imposed on the belt tensioner.
It is also known to provide a belt tightener with a fluid dampening means, such as a conventional automobile shock absorber.
For example, see the following United States patent:
It appears that the belt tightener of item (8) above does not have mechanical spring means and tightens the belt by applying rigidly interconnecting idler pulleys respectively against the slack and tension sides of the belt, the pulleys pivoting together relative to the belt with the shock absorber dampening the pivoted movement of the pulleys.
However, it is believed that the following U.S. Patent provides a tensioner for a power transmission belt that is adapted to be operated in an endless path, the tensioner comprising a support means for being fixed relative to the belt, a belt engaging means carried by the support means and being movable relative thereto, mechanical spring means operatively associated with the support means and the belt engaging means for urging the belt engaging means relative to the support means and against the belt with a force to tension the belt, the mechanical spring means providing the sole force of the tensioner for tensioning the belt, and dampening means to dampen the movement of the belt engaging means relative to the support means with a restricting force of the dampening means, the dampening means comprising fluid dampening means operatively associated with the support means and the belt engaging means to dampen the movement of the belt engaging means relative to the support means in at least one direction of movement thereof.
For example, see the following United States Patent:
It appears that the belt tensioner of item (9) above has a piston of a piston and cylinder means of the tensioner urged in a tensioning direction by a compression spring disposed within the cylinder and bearing against the piston member, the piston member being cup-shaped and the cylinder member being cup-shaped with the piston member telescoped therein and with the cavity therebetween being filled with hydraulic fluid for movement dampening purposes.